This invention relates to engine mounts for jet aircraft engines and more particularly relates to an aft engine mount that is stiff enough to provide support for the engines while accommodating thermal growth of the engine.
Typically, a jet engine is mounted beneath the wing of a commercial airliner by forward and aft engine mounts attached to struts affixed to and extending downwardly from the wing structure. The forward mount is typically rigid and thermal expansion of the engine, both radially and longitudinally, is accounted for in the aft engine mount. The aft engine mount is generally also designed to react against vertical, side, and engine seizure (torque) loads. Using previous engine mount designs, the engine mount many times exceeds the external dimensions of the cowl surrounding the engine. In such cases it is necessary to provide a local blister fairing over the engine mount fittings. Such a fairing "bump" on the cowl causes interference effects and blowing drag penalty in the engine fan exits and the wing lower surface. In some cases, the bump is as high as 2.4 inches and exhibits considerable drag on the aircraft. In addition, the construction of the cowl is complicated by the addition of the blister fairing.
The distance between the engine and the wing is fixed in the initial aircraft design and the space must be shared by the engine-mounting struts and the engine mount. The space restriction caused by the design of the aircraft tends to make the strut shallow so that any increases in the vertical height of the strut will pay off well in terms of the stiffness-to-weight ratio of the strut structure. Therefore, it is desirable that the engine mount fittings be made as low-profile as possible without sacrificing load handling and other requirements in order to both fit the engine mount within the cowl contour and also to permit as deep an engine-mounting strut as possible in the space between the engine and the wing.
It is therefore an object of the present invention to provide a low-profile aft engine mount that tolerates thermal growth of the engine.
It is a further object of this invention to provide such an aft engine mount that permits a maximum depth engine strut to be utilized in a predetermined amount of space between the engine and the wing.
It is another object of this invention to provide such an aft engine mount that meets all the usual requirements of load handling, ease of manufacture, ease of installation, and maintenance.